Master Thesis
Computer Science
Thesis no: MCS-2008:20
June 2008
Virtual reality: Effective surroundings,
Enormous demonstration and mediator system
in the games, industrial design and
manufacturing
Jawad Akhtar
Department of
Interaction and System Design
School of Engineering
Blekinge Institute of Technology
Box 520
SE – 372 25 Ronneby
Sweden
This thesis is submitted to the Department of Interaction and System Design, School of
Engineering at Blekinge Institute of Technology in partial fulfillment of the requirements for the
degree of Master of Science in Computer Science. The thesis is equivalent to 20 weeks of full
time studies.
Contact Information:
Author(s):
Jawad Akhtar
E-mail:- [email protected]
University advisor(s):
Hans Tap
Email: - [email protected]
Department of Interaction and System Design
Department of
Interaction and System Design
Blekinge Institute of Technology
Box 520
SE – 372 25 Ronneby
Sweden
Internet
Phone
Fax
: www.bth.se/tek
: +46 457 38 50 00
: + 46 457 102 45
ii
ABSTRACT
In this thesis, the concept of virtual reality has been
elaborated in the context of games, industrial design
and manufacturing. The main purpose of this master’s
thesis is to create a virtual environment for games that
are near to the reality and according to the human
nature through aspects like better interface,
simulation, lights, shadow effects and their types. The
importance of these aspects regarding realistic virtual
environment is complemented through the comparison
between two environments i.e. desktop and CAVE on
a flight simulation program.
Keywords: Virtual reality, simulation, cave, MATLAB/
Simulink, VAPS, MultiGen, Vega
1
PREFACE
We would like to take this opportunity to thank those people, who have
helped me performing the experiment and supported me with writing this
thesis, specially my supervisor Dr. Hans Tap for his support and guidance
during thesis work.
2
CONTENTS
ABSTRACT .................................................................................................................................... 1
PREFACE ....................................................................................................................................... 2
1
INTRODUCTION .................................................................................................................. 5
1.1
1.2
1.3
1.4
1.5
2
BACKGROUND..................................................................................................................... 7
2.1
2.2
3
INTERFACE OF GAMES ..................................................................................................... 11
SIMULATION AND ITS REALITY. ....................................................................................... 11
GAMES SIMULATION COMPLEXITY AND COMPLETENESS ................................................... 12
LIGHT AND SHADOWS ..................................................................................................... 12
FUTURE VR SYSTEM ....................................................................................................... 13
METHODOLOGY ............................................................................................................... 14
4.1
4.2
4.3
4.4
5
VIRTUAL WORLDS ARE UNREAL (TRUTH AND FICTION) ....................................................... 8
LAWS OF VIRTUAL WORLDS ............................................................................................... 9
PROBLEM DEFINATION/GOALS.................................................................................... 10
3.1
3.2
3.3
3.4
3.5
4
PURPOSE .......................................................................................................................... 5
RESEARCH FOCUS ............................................................................................................. 5
SCOPE .............................................................................................................................. 6
RESEARCH QUESTION ........................................................................................................ 6
METHOD .......................................................................................................................... 6
WHY USE QUALITATIVE RESEARCH ................................................................................. 14
FINDING MY GOAL IN QUALITATIVE RESEARCH ................................................................. 14
QUALITATIVE TECHNIQUES FOR DATA COLLECTION ........................................................ 15
MY APPROACH................................................................................................................ 15
THEORATICAL WORK..................................................................................................... 17
5.1
WHAT IS…….”VIRTUAL”?........................................................................................... 17
5.2
WHAT IS……”REAL”? .................................................................................................. 17
5.3
VIRTUAL REALITY ITS SELF REALITY................................................................................ 17
5.4
SIGHT AND DISPLAYING COMPONENTS ............................................................................. 17
5.4.1 Display resolution...................................................................................................... 18
5.4.2 Color resolution......................................................................................................... 18
5.4.3 Frame rate................................................................................................................. 18
5.4.4 Polygons.................................................................................................................... 18
5.5
VR SYSTEM AND ITS COMPONENT .................................................................................... 19
5.5.1 Visual Displays .......................................................................................................... 20
5.5.2 Acoustic Display ........................................................................................................ 20
5.5.3 Force and Tactile feedback ........................................................................................ 20
5.5.4 Advantages of a virtual world system are:- ................................................................. 21
5.6
DESIGNING INTERFACES .................................................................................................. 21
5.7
USER INTERFACE OPTIMIZATIONS ................................................................................... 21
5.7.1 User interface properties............................................................................................ 22
5.7.2 Evaluate a User Interface Design ............................................................................... 22
5.7.3 MOHAA vs. BATTLEFIELD 1942 .............................................................................. 23
5.7.4 Avatar Appearance .................................................................................................... 23
5.7.5 Facial Expressions..................................................................................................... 24
5.7.6 Non-verbal Audio and Language-based Communication............................................. 24
5.7.7 Overall Environmental Details ................................................................................... 25
5.8
SIMULATION AND ITS CONCEPTS ...................................................................................... 25
5.9
MODELING & SIMULATION ............................................................................................. 25
5.10
SIMULATION CONVENTIONS ................................................................................... 25
5.11
TYPES OF SIMULATIONS .................................................................................................. 26
5.12
THE PHYSICAL SIMULATION ................................................................................... 27
5.12.1
COMPONENTS OF THE PHYSICAL SIMULATION ............................................. 27
3
5.13
REACTIVE SIMULATION ................................................................................................... 27
5.14
CONTROLLED SIMULATION .............................................................................................. 28
5.15
PARALLEL SIMULATION .................................................................................................. 29
5.16
VARIABLE RATE UPDATING .................................................................................... 29
5.17
LIGHT AND SHADOWS ..................................................................................................... 30
5.17.1
Visual Perception: What We See Is Not Always What We Get ................................. 30
5.17.2
Clock layout .......................................................................................................... 30
5.18
LIGHT QUALITY .............................................................................................................. 31
5.19
LIGHT DIRECTION ........................................................................................................... 32
5.20
LIGHT TECHNIQUES ......................................................................................................... 33
5.21
TYPES OF SHADOWS ........................................................................................................ 35
5.22
OPENGL AND RADIANCE ................................................................................................. 35
5.23
FUTURE TECHNOLOGICAL DEVELOPMENTS ....................................................................... 36
6
EMPIRICAL STUDY .......................................................................................................... 38
6.1
GENERIC MODEL ............................................................................................................. 38
6.2
SOFTWARE AND HARDWARE ............................................................................................ 39
6.3
EXPERIMENT DESIGN ...................................................................................................... 40
6.4
SYSTEM OVERVIEW ......................................................................................................... 40
6.5
USER INTERFACE ............................................................................................................ 40
6.6
TRAINING ....................................................................................................................... 41
6.7
EXPERIMENTS ................................................................................................................. 41
6.7.1 CRT- Experiment ....................................................................................................... 41
6.7.2 Cave- Experiment ...................................................................................................... 42
7
RESULTS ............................................................................................................................. 43
7.1
7.2
7.3
7.4
8
TASK PRESENTATION ...................................................................................................... 43
QUESTIONNAIRE ............................................................................................................. 43
PARTICIPANTS PROPOSAL................................................................................................ 44
OBSERVATION ................................................................................................................ 45
OVERALL DISCUSSION ................................................................................................... 46
SUMMARY .................................................................................................................................. 48
REFERENCES ............................................................................................................................. 49
APPENDIX ................................................................................................................................... 52
4
1
INTRODUCTION
__________________________________________________________________________
“A picture is an intermediate something between a thought and a thing.”
- Samuel Taylor Coleridge
1.1
Purpose
The purpose of this study is to practice interactive design in the context of virtual
reality and its effectiveness and enormous surroundings, which is used in the
designing of games, industrial design and manufacturing.
It will totally focus on the effective environment, enormous demonstration and
realism in computer games, industrial design and manufacturing, because this is the
requirement for future simulation of any product. It’s also helpful for simulate certain
aspect of reality in the real time and with accurate precision and perfect simulation
e.g. flight simulator, online virtual conference etc.
This paper provides demanding information to evaluate difference the two
environments of enormous demonstration field of view according to the user’s
perspective. The other way to see if the virtual environment surrounds the user
peripheral field of view or if the user feels like he is standing in front of it.
1.2
Research Focus
Virtual reality is a new technology for interaction in environment with simulation,
design, entertainment, and many other pursuits. The purpose of our paper is to
identify weaknesses and how interface simulation and light shadows effective in the
virtual reality. We will point out the current solutions to problems in these areas,
possible areas of improvement, and those problems that remain completely
unsolved at this point.
In real time rendering require the generation of at least 20-30 frame/sec, if we are
viewing in perspective views. Its mean user can watch the three sides of an object at
same time is called perspective view. So right now we still need more deeply
research for creating / developing real objects, and its simulation. Our research is
focus on virtual environments and its effectiveness of the surrounding for the user.
Which are helpful in designing games, industrial design and manufacturing e.g.
interface, simulation and light-shadow?
Today the importance of Virtual Reality has broadened and includes three types of
techniques.
1. Immersive
2. Semi-immersive
3. Non- immersive (monitor)
5
When we talking about the immersive VR system refer to the walls display devices
or a type of flat projection devices it refers to CAVE and HMD, both these display
systems produce very broad FOV (field of view), but in this paper we only focus
CAVE instead of HMD. Although it is very clear HMD has the potential to provide
higher immersion than the cave, but the HMD actually FOV is smaller. But my
motivation to check or enhanced the environment with the help of experiment. The
experiment will perform on the two immersive and non- immersive environments.
Immersive environment is called CAVE and the non-immersive environment is
called monitor.
1.3
Scope
The field of VR initially focused in immersive viewing via expensive equipment, For
example, artifacts for creating car models are expansive so it is better to create
virtual artifacts which is near to reality and can be tested for quality with less
difficulty and with less cost.
That is why this thesis is helpful for creating new ideas and advancement in realism
such as aircraft pilot training, computer games, manufacturing design, tele-operated
vehicles, engineering and scientific visualization
1.4
Research question
This thesis wills discuss the following question and problems.
1. What are interface and its current realism of computer games?
2. How can the accuracy of an object be improved by better simulation
3. How can we improve the completeness and complexity of simulation?
4. Why light and shadows quality are not effective.
5. Future technological development in the form of product and VR system.
1.5
Method
In this thesis, my approach is to find the result with the help of collecting data from
the literature study, and this research comprises of procedure like data collection,
which include observations and the participation contribution, the comparison of two
different environments to find the empirical result and some questionnaires from the
participants.
After critically observe the surroundings and the participants contribution in the
virtual environments, we will give you the result in the form of both environments
average results output and the chat table.
6
2
BACKGROUND
__________________________________________________________________________
The first idea of virtual reality was come into the mind of Ivan Sutherland around
since 1965; when Ivan Sutherland expressed his ideas of create virtual or imaginary
worlds. At MIT, he conducted experiments with three dimensional displays [7]. He
developed the first system to surround people in three dimensional displays in 1969
[7]. The concept of virtual reality was mainly used by the United States in between
70 and late 80s [7]. This concept is used for military purpose to train pilot through
flight simulator. But the rest of the world did not show attention in this new
technology [7].
“A computer generated simulation of 3-dimensional environments, in which the user
is able to both view and manipulate the contents of that environment.”
Virtual reality is very useful idea to create the environments and provides a deep
knowledge for designing games industrial designing and manufacturing field. Due to
this, it can be very helpful for practitioners their customers and the research student
in a number of innovative ways.
In the beginning, there were a number of terms for the new field: artificial reality
(Myron Krueger, 1970s), virtual reality, and cyberspace (William Gibson, 1984),
actually VR has been done for over 10 years. [3]
Below is a list of key dates and people who have made their mark on the virtual reality
historical timeline.
Year
Person(s) Responsible
Accomplishment
Why it was important
1965
Ivan Sutherland
Ultimate Display
The beginnings of VR
1977
Dan Sandin, Richard Sayre
and Thomas Defanti
The first dataglove
Interaction through body
movement
1982
Bonnie MacBird (Writer)
Tron
The first computergenerated movie
1983
Myron Krueger
Videospace
First virtual environment
Neuromancer
The term 'Cyberspace'
1984 William Gibson (His assistant)
1987
Michael Piller (Writer)
Star Trek - The Next
Generation
The Holodeck, idea of
immersive VR
1992
Stephen King (Official
Website)
Lawnmower Man
A look at the possible
negative side of VR
1995
Silicon Graphics
VRML 1.0
Virtual Reality Modeling
Language
1999
Larry and Andy Wachowski
The Matrix
Virtual Reality movie
grosses $750M
worldwide
http://www.bilawchuk.com/mark/history.html
7
2.1
Virtual worlds are unreal (Truth and fiction)
Virtual reality is not magic but someday it will very near to the reality and it is
always facing challenges about the concept of reality. VR is based on computer
graphics simulation, and other existing techniques and it will be more powerful
depending on the development of new technologies.
Virtual worlds are artificial, imitation, imaginary, insubstantial, and invented. If
we put all these condition so far virtual worlds are real, as well. All things synthetic
or imaginary do not fall entirely outside the ambit of reality. If they did, we would
require to banish from reality all manner of human actions and creations, including
buildings, languages, laws and most important for our purposes [4]
Virtual reality is in the process of leaving the area of purely academic research.
The industry is evaluating its potential in design, development, and manufacturing
processes.
Virtual reality is totally based on trio based idea, immersion, interaction and
imagination, Adapted from Burdea [1993], Fig below.
If you can imagine any thing, this is possible to interact with your own imagination
and you can immerse with sound, pictures and tactual effects in virtual environment
with the help of virtual reality.
Immersion
I3
Interaction
Imagination
Virtual reality triangle
Three-dimensional simulations of reality in cyberspace, where people move,
lived, worked, act and socialized. The development of these virtual worlds has been
motivated by the game, industrial design and manufacturing that is why we can say
that, now that types of world are used for far more than play, and very soon they will
be widely adopted as spaces for research, education, politics, Aircraft pilot training,
computer games, manufacturing design, tele-operated vehicles, engineering and
scientific visualization work. In some aspects coming year our gateway maybe to the
Internet and it look more like a video game and less like a book. Nobody assume
that exactly where the future of VR is heading but it is clear anyone understand the
value/future of the Internet needs to understand virtual worlds.
Millions of people around the world play in these virtual or synthetic worlds.
According to the balkin information figure, 20 to 30 million regular participants now
spend more time in virtual environments as compared to their real world jobs or
engaged with their real-world environments/communities [4].
8
According to balkin finding the average number of hours played are almost 22
per week. People who do not participate in real breathing space excitedly do so in
virtual spaces, because of new adventures, new identities, and the possibility of
building new social universes [4].
2.2
Laws of virtual worlds
There are three primary reasons of law of virtual worlds.
First, virtual worlds are
attracting
an
everincreasing population of
participants who believe
that the social interactions
that occur within these
environments
are
important. [4]
Second reason why virtual
worlds are worthy of
consideration is that the
economic
boundaries
between the real and the
virtual world are not as
distinct as they might
appear. [4]
Third reason for exploring
the laws of virtual worlds
is that they provide a
parallel
alternative
to
existing legal systems,
where new forms of social
regulation
can
be
explored. [4]
Previously VR is more convergence disciplines as compare to the new branches of
technology that’s why it’s simply appear in fresh look at human interaction. This is
only possible due to the developing of user interface design, simulation and a better
visually telepresence technologies. It can be totally dependent on the experiences of
the human participant.
9
3
PROBLEM DEFINATION/GOALS
__________________________________________________________________________
Here we are defining the problems and goal according to the thesis topic. The
success of any goal is reliant on the definition of problem, identification, root cause,
quantification. Before explanation of the question and its purpose, we are going to
explain the goal, this paper focus on the visual realism, image resolution, frame rate
and the latency and its simulation in the games but the context of the virtual
environment.
•
To increase the level of realism in a scene considerably, in order to
make a believable environment.
•
We are trying to find the best application of this technology, which
results in the form of viewer not noticing any transition or
discrepancies between real footage and computer generated effects.
•
Providing high level of detail and sophistication is extremely complex
and requires a great deal of rendering time.
•
Computer generated images consist of discrete picture elements or
pixels.
•
The size and number of pixels depend on the display size and
resolution.
•
At higher resolutions the discrete nature of the display becomes less
apparent, however, the number of pixels in the image becomes vastly
greater.
•
As the color and intensity of each pixel must be generated
individually, this puts a heavier load on the graphics system.
•
To give the impression of a dynamic picture, the system simply
updates the display very frequently with a new image.
•
This system relies on the human phenomenon of persistence of
vision.
•
Normal television broadcasts update at a frequency of 50Hz in the
UK - 60 Hz in the US.
•
This means that in order for a virtual environment to appear flicker
free, the system must update the image greater than 20 times each
second >> a heavy load on the graphics system.
•
The most important aspects which must be addressed to make the
environment not only more realistic, but simply tolerable.
•
Latency or lag is the delay induced by the various components of a
VR system between a user’s inputs and the corresponding response
from the system in the form of a change in the display.
10
3.1
•
As latency increases, a user’s senses become increasingly confused
as their actions become more and more delayed.
•
Chronic cases can even result in simulator sickness, a recognized
medical problem associated with virtual environments.
•
Latency must be kept to a minimum in order to create a usable VR
system.
Interface of games
Games are very popular for people at all ages, no difference between male or
female. The purpose of gamming is not only for enjoyment or pleasure. It’s also use
for education and brain training.
There are many types of games like 3D, Action, adventures, arcade, Brain Training,
Dancing & Shows, Hot, Learning, Motor sports, Multiplayer, Political, Puzzle,
Racing, Shooting, Soccer, Sports and simulation etc.
The attractiveness of games is based on the user friendly interface. The question is
arising how can we evaluate, which games attractive for playing or not, what are
factors involve to generated the way to positive affect on the user, either its depend
on the user entertained or others. If game is not entertaining then you can say
easily, that game is neither motivating nor attractive.
More the interface effective, more the value of software games, same as that of
designing of function and performance. What is the requirement of attractiveness in
games? How can we check the fun and instrumental aspect of games? How can we
calculate the usability in the sense of user friendly, natural, look and feel and more
perceptive view?
The purpose of these questions are to find the solution of design and advance
interface of games and how can we improve the realism of current games, because
the communication between player and game is depend on the reality, and we am
sure if games will more realistic, more player will playing games with full enjoyment.
3.2
Simulation and its reality
First of all what is simulation and how can we differentiate between simulation and
modeling?
Modeling is a computer generated process to explain the imaginary movement of
any polygon shaped in a virtual world. But simulation concept is entirely different
from the modeling in virtual reality.
A simulation is a process of an imitation of some real thing, state of affairs or
apparatus to generate test condition that approximates real or operational condition.
It can be representing different characteristics or behaviors of a real thing, e.g. flight
simulator, second life and Medal of Honor etc.
11
Now the point is come, where the simulation is embedded or involve in computer.
The answer is, in computer games, industrial product design, manufacturing fields
and many more.
How can we say that, simulation is effective in the virtual enviroment? This is totally
depending on the comparison of real thing to the simulated object.
So we can say that the only question is able to answerable now a days, what is the
reason that our simulation is not provide an effective results, what is the concept of
simulation, how they work and tools are helpful for creating the simulation, either
simulation is hardware dependent or not.
3.3
Games simulation complexity and completeness
Games does not work its self, its can be control by the help of different components
are called infrastructure and the especially simulation is entirely part of many
algorithms and data structure. These components and their relationship give a
complete architecture of the game. But one thing is very important that each and
every concept, and architecture is different to the other games Here we are give you
the brief description of problems of simulation and its complexity. What factors are
involved to producing the real simulation in games? Here we are discussing the
simulation types, physical simulation and games simulation [11].
Physical simulation has different attributes of an object as compared to the game
simulation it has more abstract perception. Under this question will describe the
terminologies used in simulation.
3.4
Light and shadows
Lightning is one of the most important things in Computer Graphics-art. One big
problem was lighting up the scene.
In short three lightning techniques are:
•
•
•
The three lights scene,
The sphere of lights and
Lightning with mental ray.
The three different lights are:
• Key-Light
• Fill-Light and
• Back-Light
Now the question is arise how the light works and come into and out of the eye. We
mean what is the technical procedure. When you look at a physical surface, your
eye's perception of the color depends on the distribution of photon energies that
arrive and trigger your cone cells [9]. Those photons come from a light source or
combination of sources, some of which are absorbed and some of which are
reflected by the surface. [9]
12
In addition, different surfaces may have very different properties • Some are shiny and preferentially reflect light in certain directions [9].
• Some are scatter incoming light equally in all directions [9].
• Most surfaces are somewhere in between [9].
Shadows are an important way to add realism to a scene [10]. There are a number
of trade-offs achievable when rendering a scene with shadows. Shadows are
composed of two parts, the umbra and the penumbra. Fig below The umbra is the
area of a shadowed object that isn’t visible from any part of the light source. The
penumbra is the area of a shadowed object that can receive some, but not all of the
light [10]. An easy-to-implement type of shadow can be created using projection
transforms [8].
Why light and shadow are not real, we will try to find the valid problem of light and its
shadows, its size and limits, through the help of type and its techniques, more over
we will discuss the latest technology like OpenGL and RADIANCE
3.5
Future VR system
What is the meaning of technology, and how can we differentiate the term science
and technology. The term technology has the multiple meanings, but according to
the Microsoft’s Encarta 1995 encyclopedia: “Technology, it is a process by which
human beings fashion tools and machines to increase their control and
performance” [12].
Here we will starts the research on the future technologies in the field of games in
the context of virtual reality and its systems. The term technology is not only use for
hardware, it also used in the term of, the study or technique for better output.
Technology is also conceived for both conditions like creative and destructive
process
13
4
METHODOLOGY
__________________________________________________________________________
Research is a systematic way to find the one or more solution of any problems or it
can be define like that to find the answer of question in structured way. When
anybody withdrawing to prepare research, they always understands the background,
questions and the way they are starting, which are comparative helpful for finding
that goal.
4.1
Why use Qualitative Research
In order to find out the solution or to gain specific information in attempt to answer
the specific questions, qualitative research methodology will be used, but the result
of this type of research is based on the experiment and out of two experiments one
is done with the help of participants and the other is done by the help of previous
research.
The reason to adopt this methodology is that, we have to perform an experiment in
the form of CRT environment, but as compared to the cave are need proper
environment and it is more expensive in the sense of hardware. That’s why my idea
to compare the two environment on the basis of previous research and some
questionnaires. It is less expensive as compared to the practical quantitative
research or an effort to prove some numerical result or data. The more important
aspect of this research they give you flexible time and distance, and you don’t need
many interviews and meeting for gathering data, we just perform an experiment
through some participants. Infect my aim in this topic is to find out the quality of the
research, or to have some clear ideas about the issues related to reality in games.
So in order to perform research in such type of type, we repair to have consider to
gathering data, analyze to data and then come up with some comprehensive result,
which depicts information regarding the solution of the proposed research questions.
Qualitative research comprises of procedure like data collection, which include
observation, in which the researcher critically observe the surroundings and the
participants which are engaged in some natural happenings and the observer it
become a participants and fires to have a feel of the whole system itself.
In this way the observer can better extract useful and vital information by expecting
itself and also by observing others. The other way of collecting information is
through interviews, in which observer tries to read the mind of the peoples whom he
is interviewing and also by telephonic calls in another way.
One more ways to collecting data or information regarding research to have an idea
about the quality of the topic is that researcher tries to read document, articles,
research paper and books
4.2
Finding my goal in qualitative research
In order to perform qualitative research, its mean you want to explore a topic or
given a new idea on the behalf old with the help of questionnaires and my
14
observation. Then you cover the target audience, people motivation culture and its
behaviors. Important point why we are going to start, select this topic and what the
result comes out. Weather you are doing quantitative or qualitative research it’s
totally depend on the assumptions and your appropriate method for your research.
4.3
Qualitative Techniques for Data Collection
Many researchers prefer the term Empirical data, which are directly belong with
qualitative research, because qualitative data is non- numeric. There are different
techniques for data collection like interviews, observation, published and
unpublished articles and documents, daily or weekly reports, many more
Here is new a concept of sources, primary experiment and secondary source, that
experiment which are not had been done before are called primary experiment, and
the sources which are published are called secondary data
4.4
My approach
My approach is to find the result with the help of collecting data from the literature
study, the comparison of two different environments to find the empirical result and
some questionnaires from the participants. We will start my thesis from the very first
chapter, the background, then Problem definitions, theoretical work and in the last
chapter will the comparison of the two environments. Two out of one environment is
my contribution and the other is the previous concepts. The actual purpose of this
empirical study to find the environmental interactions of one or more individuals,
groups, to observed and analyzed for virtual environments and its effects according
to the research questions in relation to internal and external influences.
Qualitative research comprises of procedure like data collection, which include
observation and empirical results. In which the researcher critically observe the
surroundings and the participants engagements in virtual environments and the
observer also a type of a participants feel of the whole system itself.
Flowchart of experiment design
15
According to the above flowchart, it is necessary for research to get the knowledge
and know how of that topic, then write the question which is not even solve or need
updating. Check how can you start the research procedure, this is called design
experiment, the third step is collection of data, there are different ways of data
collection like reading books, interviews, observation, published and unpublished
articles and documents but there are two main types of methodologies for collecting
data, one of them is observation and the other is experiment.
The important point, not every piece of data is useful according to your requirements
and your research. So be careful before, when you starts collecting data. Now the
second last stage is very significant for data, is called analyzing the data. If you find
the right data for your right search then you able to find the answer of the first stage.
Otherwise you couldn’t find the solution of the problem.
16
5
THEORATICAL WORK
__________________________________________________________________________
This chapter gives you a tangible knowledge of the sight and displaying components
in the virtual environment. This chapter does not focus on the entire VR systems but
it explains only the basic knowledge of the VR component from the reader
perspective. After having some understanding of how the VR system and its
component works, then we will discuss the proposed research questions and their
possible solutions.
5.1
What is…….”VIRTUAL”?
The term virtual is frequently used in the computer industry to pass on to something
that is simulated in software, e.g. virtual memory. Now this concept will come into
the name of virtual reality for computer-based simulated environment. The question
is how the virtual environment will simulated exactly to the real world. The answer is
the concept of real environment is embedded into the virtual environment like,
gravity, topography, locomotion, real-time actions, and communication [13].
5.2
What is……”REAL”?
Our all perception of the world come through five senses, touch, smell, taste, sight,
hearing and further more virtual reality doesn’t only these five senses they also need
environment effect like wind effect, gravity, pressure, weather effect etc. and the
most important thing is that not all the senses is not equally important for example in
virtual world we couldn’t feel the taste of any thing, because we are in the virtual
world.
5.3
Virtual reality its self reality
Virtual reality is a next generation human computer interface. In early days its very
costly VR system but now very cheap systems can now be assembled. The reality
can be generated with the help of VR systems, visual world, auditory world and
tactile world. Now we can describe how system is working [14].
5.4
Sight and displaying components
Out of five senses sight is very important and main emphasis in the VR research at
the present time of graphics area. Realistic images are an important part for
producing real simulation. This is only possible by the used of display and color
resolution and frame rate of simulation. Display resolution is the number of dots
called image.
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5.4.1
Display resolution
The higher the resolution, the more realistic images appears. Below table give you a
brief information related display resolution depending on the video graphic adaptor.
Low VR system
Television graphics
High resolution PC
High resolution workstation
Computer generated images for film
HMD use LCD color
5.4.2
320 columns by 200 rows
640 columns by 480 rows
1024 columns by 768 rows
1280 columns by 1204 rows
4096 columns by 4096 rows
170 columns by 140 rows
Color resolution
Color resolution is the number of different colors the computer can display
4-bit display
8-bit display
16-bit display
24-bit display
5.4.3
16 colors
256 colors
65536 colors
Over 16 million colors
Frame rate
The frame rate is also very important for realism, the number of images per second
that the computer can update the entire screen with new image. Television update
screen every 30 time per second, film seen updates every 24 time each second and
cartoon use 3 to 4 frame per second. So we can say that higher the frame rate lower
the resolution and vise versa [13].
.
5.4.4
Polygons
A polygon is the object made up of many sides. If you have more sides of polygon
its mean your polygons is smoother. Today mostly system used polygon graphics.
So if you more polygon side its mean your computer need more time to computes to
done to draw an object. When you create any polygon the next point is realism, the
techniques is called texture mapping, ray tracing and radiosity [18]. See figure below
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A ray-traced image
5.5
3D object
texture applied 3D object
VR system and its component
A virtual world is work with the modulator workstation and it communicates 3D
spherical and presence of operator, but we cannot say that we can always make
destination. If we talking about successful reality and its simulation it is neccessary
virtual system completely depend on the integration coupling between VR system
and the operator by human [14]. (Figure 1)
Figure 1 Basic Virtual Man Machine Interface [14]
The main demanding area is visual channels of the computing requirements.
According to the human knowledge this is very complicated work like stability, field
of views, left and right eye demonstration, color difference check and its resolution
settings [14].
Visual display (HMD)
Headphone speakers
Force and Tactile displays
Other out put devices (e.g.
heat sinks olfactory displays)
User
Figure 2 Output effectors
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Output technologies for the virtual environments do not have to accurately
reproduce the distal stimuli from the real world objects that are to be portrayed in the
virtual environment; instead they have to present proximal stimuli that incorporate
those features to generate the desired percepts in the user [15]. Show the output
effectors shown in figure 2.
5.5.1
Visual Displays
Displaying images to the user of a virtual environment requires as image generator,
an image source, and an optical system. There are different types of visual display,
if image is viewed by the both eyes is called monoscopic, if different images are
presented to the two eyes is called stereoscopic and the images display system
have two lenses is called objective lens, and the eyepiece, which is use for
magnifies the images [15].
A computer synthesized graphic generated by the visual display system and provide
to the user with help of helmet-mounted display. The HMD is fully occupied with
visor, eye-glasses or 1 or 2 small displays with lenses or you can say that semitransparent mirrors embedded in a helmet. This can explain the position in the form
of x, y, z changes of angle, movements, rotate or elevation after that it can be
transfer into a high performance graphics system. In HMD a visor is present which is
used for configure the appropriate view of the world whenever or wherever the user
looking. This display device is binocular (it’s a mirror-symmetrical telescopes) device
give us a wide view, display resolution, colors etc [14].
5.5.2
Acoustic Display
The audio sources comprise a speech synthesis, sound synthesis, audio synthesis
and digital sounds. These all are used for input and control the audio sound. The
audio synthesizer take into account head line of sight, acoustic masking presented
by the user of head and ear shape, it’s responsible for the synthesis and the 3D
auditory localization [14].
The Speech of the user can come from the three sources.
• Transmitted speech from the other synchronous user of the virtual
environment
• Prerecorded speech
• Synthesized speech [14]
5.5.3
Force and Tactile feedback
Force and tactile display for the virtual environments are possible by either attaching
display devices to the user or letting the user grab or otherwise make contact with
the display devices [15]. It gives you an accurate and ordinary response through
tactile stimulation. So the user move hand any position either any angle either move
finger all are display on the HMD helmet mounted display. By displaying virtual
control panels then it is possible to interact with the virtual controls. When you enter
the virtual world you can grasp the object with your own hands and you can feel the
object and tactile give a feedback when user feels resistance [14].
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Its totally depend on the user task; either he/she need or not feedback from the
tactile. Head and hand coupled unit give you the interface between the man virtual
world generators. [14]
There are different types of constructional and functional requirements for force and
tactile feedbacks. So the hand movements are often used by the following
categories.
• Strength and durability
• Fit and calibration to the different size hands
• Capability of response at sufficiently high frequency
• Sufficiently low work to rest ratio and force in order to avoid user fatigue
• Adequate sensitivity [15]
5.5.4
Advantages of a virtual world system are:-
1. They provide an extensive field of view and auditory 360* medium.
2. Provide exact real control interface
3. Use 3D spatial capabilities of the human being
4. It can be Software reconfigurable.
5. Have wide application [14].
5.6
Designing interfaces
Interfaces consist of the display information and accept user input. Its components
are not part of the games. This includes menus, dialogs, in HMD, buttons and tool
bars. Normally games have much more complex interface, because their larger
screen resolutions and input combination of keyboard and mouse. Moreover, games
windows are special surfaces that use OpenGL, DirectX, or other hardware
accelerated drawing [16].
5.7
User Interface Optimizations
The games interfaces concept is same as in non-game applications, but the
implementation are quite different, actually mostly games need many loop and
redraw concept, each frame redrawn by the UI, its mean when UI feel changes or
when user interact in the games then UI redrawn the frame. So we can say that
games interfaces is much more complex and tough performance requirements as
compare to the other type of UIs. The reason is that in normal UI the user only
literally changes can takes but in games need many changes to redraw the frames
[16].
There are different types of techniques to solve the complex user interfaces. Now
we can tell you the basic properties of User interfaces and its evaluation.
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5.7.1
User interface properties
Many professional have a goal of designing a good UI games, but this will only
happened if developers follows the UI properties, to understand the people
perspectives and behaviors. Here ill give you the important points that are helpful for
designing games [17].
Design should be clear mean every menus and its functionality are mentioned and
its design should be consistence. Be careful of different perspective of identification
of any message and its behavior, interface is effective if they provide a visual feed
back [17].
Be careful, while input the audios and sound in the games, you should be consider
what type of sound is fit in which environment, what sound create a problem of the
user [17].
Before entering the game stage, showing some type of description about stage and
how to complete this stage, its only applicable if text is clear and easily to read by
the user eyes.
Provide a proper guide line with the help of maps and compass, provide mouse,
keyboard and more important joysticks support for better performance. Last but not
least property of the interfaces in game, is game model should be the presentable
with continuity and control are easy to handle for the user or any player [17].
5.7.2
Evaluate a User Interface Design
Designing a good interface is a challenge for any programmer [19], because the
user capabilities and its need depend on the technical requirements of the product.
And the only thing is considerable for the user is called interface of the game. There
are many types of game like Civilization, racing, simulation and strategic. Nowadays
the user is totally focus on the real strategic game, real judgment of information and
situations [19].
The meaning of the games is not even the enjoyments and fun, it is flexible and
easy to learn. Computer games doesn’t mention the design, more than that of it an
attractive interface. If the games are visually effective and artistically inspired than
user can say that game have an attractive and easy to play [19].
If the game options and its menus are not clear, we don’t think so, it is considerable
to the user to play that game. Check whether simulation, analyze user procedures
required by design or not. Measuring time required for loading environments [21]. In
short games are directly proportional to interface, because they are helpful for better
play performance in the game. But we couldn’t say that, if you can follow this type of
interface properties and you can apply these properties each type of games, e.g.
Rebellion also fails miserably to provide feedback [19]. For instance, when a mission
is sent into enemy territory, there is no visual sign that the mission is underway, in
many games the control and interface is according to the standard but still user can
not feel comfortable while in the game [19]. The basics problem in these games the
designer forget the usability in the favor of other properties of interface like ease of
22
use, performances and good cognitive mapping. So in some aspect the game is
easy to watch but not fun to play [19].
5.7.3
MOHAA vs. BATTLEFIELD 1942
The purpose of this question to find the fact that lack of perceptive interface cues is
one of the distinctive features. In this section ill give you the comparison in between
two games Medal of Honor (mohaa) and battlefield 1942 interface differences. It is
an only way to interact with player- player and player- environment interaction [22].
Now the both games are 3D shooter game, supported with multiplayer environment
and the player can play this game by the help of first person and third person view,
with diverse soldier sketch and different type’s war equipments/ machines [22].
Interaction has been studies in several fields with different names [22]. This concept
is gives you the overview of each and every interaction relationship with the model
and some evidence of screen shot give you the events and comparisons of the
interfaces. The basic purpose of comparison in term of players interest in the games
design of interface and we can tell you interfaces is does not mean the menus
portion, the main purpose is interaction of user in the games interface, given below
the snapshots of the games, left snap of MOHAA and right is BATTLEFIELD 1942.
5.7.4
Avatar Appearance
Avatar Appearance has at least two main forms in the game. First, it provides visual
team information to other players [22]. Second, the appearance allows the players to
identify different roles in the game [22]. So the avatar appearance of battlefield 1942
is better than the mohaa. Because battle field give you the detail presentation of
avatar appearance as compare to mohaa this give a carton appearance.
23
Figure 6 Representations and visual characteristics of players [22].
5.7.5
Facial Expressions
Facial expression of an avatar based on the photo realistic face with slight dynamic
changes in expression. There are many changes like blinking of eyes etc are not
directly by the players, but some of them is controllable, such as getting injured or
killed (e.g., grins) and when initiating certain pre-defined radio messages (e.g., when
shouting "Go Go" the mouth is almost lip-synched) [22]. According to my
experience in the both games, the facial expression in mohaa game is not
proper, as compare to the battlefield mostly expression is good, illustrated in
figure 7.
Figure 7 Different facial expressions (neutral, grin, squint, and “lip-synch”) [22].
5.7.6
Non-verbal Audio and Language-based Communication
Non-verbal audio, in Battlefield 1942 an in mohaa, includes the sound effects of
various actions, such as shooting, running, jumping and reloading. Only in
battlefield, different vehicles and weapons make specific and often recognizable
sounds. In battlefield, an approaching tank is clearly indicated by the roar of its
engine and noise from its tracks. Non-verbal audio would seem to be a very
important interaction, especially in fast action games [22].
Spoken or written communication, during the battles of Battlefield 1942 and in
mohaa, is mainly handling with predefined voice messages and text-based chat
channels, mostly general messages filling the audio space of the game
environment. Textual chatting is an additional form of exchanging information in both
games, but due to the typing effort, would seem to be used less, we think in order to
improve communication in the games, use some hardware like headphone or some
voice software for transferring the voice to the other player in the game [22]. There
24
is no map overview in mohaa as compare to the battlefield; player can
observe each and every movement through map and compass.
5.7.7
Overall Environmental Details
Environmental interaction forms include the use, modification and affect of the
environment and the objects within. The environment limits the playing area in the
form of boundaries, it affects the player performance (e.g., water, visibility), and it
offers protection for the players in the form of additional scenery (e.g., colors,
textures, and objects) [10]. The environment also contains key locations (i.e., bases
that can be invaded or defended) and service areas (e.g., healing, vehicle fixing and
ammunition reloading) [10]. In mohaa player couldn’t crouch but in battlefield is
available, missions are same in both games. The environment detail is more realistic
in battlefield as compare to the mohaa. There is a tool tip in battlefield mission to
describe the mission statistic, where and which key and action is better, but in
mohaa is not included to the update version. There is no option for the player to
rebirth in mohaa but in battlefield player as he as area captured, the rebirth places
creates.
5.8
Simulation and its concepts
The Latin verb simulare means to imitate [23]. A simulation is a process of an
imitation of some real thing, state of affairs or apparatus to generate test condition
that approximate real or operational condition. It can be representing different
characteristics or behaviors of a real thing, e.g. flight simulator, second life etc.
There are many different simulation techniques, including stochastic modeling,
system dynamics, discrete simulation, and role-playing games. Despite the
differences among them, all simulation techniques share a common approach to
modeling [23].
5.9
Modeling & Simulation
Modeling and Simulation is a discipline for developing a level of understanding of
the interaction of the parts of a game or a system. Modeling and Simulation is also
very much an art form. One can learn about riding a bicycle from reading a book. To
really learn to ride a bicycle one must become actively engaged with a bicycle.
Modeling and Simulation follows much the same reality. Skill and talent in
developing models and performing simulations is only developed through the
building of models and simulating them [25].
5.10 SIMULATION CONVENTIONS
When we talking about the simulation, it is important to identify any parameters of
multiples values and trying to integrate system have different underlying
25
assumptions about who the physical world works is very difficult. It is best approach
to identify any ambiguities and solve the before writing any simulation code [16].
In a 2D simulation, the properties of the physical world can vary X and Y axes run,
and term is use for rotation, positive turn is clockwise or negative turn is
counterclockwise. But in a 3D world, there is an additional Z axis to deal. Here we
are talking about the use a standard set of rules for 3D simulations called the
Cartesian coordinate system. In this system, the positive X direction is to the right,
the positive Y direction is up and Z is backward and positive turn is clockwise and
inverse [16].
The simulation code is also use 360-angle, but in some situations to reverse the
rotation direction. The utility function Radians has this conversion built in figure
below illustrates the conventions [16]
Figure illustrates the 360-angles with radians [4]
5.11 Types of simulations
Generally Simulations come in three styles: live, virtual and constructive
Live simulations
Virtual simulations
Constructive
simulations
Typically involve humans
and/or equipment and
activity in a setting where
they would operate for
real. Think war games
with soldiers out in the
field or manning command
posts. Time is continuous,
as in the real world.
Another example of live
simulation is testing a car
battery using an electrical
tester [24].
Typically involve humans
and/or equipment in a
computer-controlled
setting. Time is in discrete
steps, allowing users to
concentrate
on
the
important stuff, so to
speak. A flight simulator
falls into this category
[24].
Typically do not involve
humans or equipment as
participants. Rather than
by time, they are driven
more by the proper
sequencing of events. The
anticipated path of a
hurricane
might
be
"constructed"
through
application
of
temperatures, pressures,
wind currents and other
weather factors [24].
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5.12 THE PHYSICAL SIMULATION
In games, there are conceptually two simulations that are closely related. First is the
physical simulation of the world. This deals with the physical nature of the world and
objects within it with respect to the rules, such as position, size, and velocity.
Second is the game simulation, which deals with the specific properties of objects in
the world in regard to the actual game, such as hit points, magic, or experience. The
proportion of each type of simulation varies enormously between different types of
games. Some games are almost entirely physical simulations that deal with cars
racing down tracks or tanks firing guns. Some games are almost entirely game
simulations that deal with points or virtual cash. Most games fall somewhere in
between. Since the game simulation sits on top of the physical simulation, there
should be a robust physical simulation in place before implementing the game
simulation [16].
5.12.1 COMPONENTS OF THE PHYSICAL SIMULATION
Physical simulations consist of rules, information and object these all components
inhabit the games worlds. When we talk about the implementation phase in games,
physical simulations also often include a collision system [16].
Rules are the information that describes how the simulation works and how the
objects in the simulation interact with each other. Physical simulation is based on
existence of the entities of simulation objects. These entities must behave with the
rules, but within that limitation, and these rules varying the characteristics of and the
behaviors that can be driven by higher-level systems such as artificial intelligence
and player input [16].
Simulations can be 3D (e. g., first person shooters and flight simulators), or 2D (e.
g., many arcade games and puzzle games), but in each case, many of the
underlying concepts are the same [16].
5.13 Reactive simulation
When we talk about reactive simulation, both the simulation and the simulation
objects are built in a low-level language. Here we are discussing simulation with the
concept of Python, it is used for decision making and behavior as the simulation is
running, but no state actually resides on the Python side. It is only used to describe
the behavior of objects that already exist in the physical simulation [16].
For example, when a door is opened in the simulation world, this Python code could
set other high-level events in motion in the simulation, such as spawning a monster
to attack the layer, but the simulation would then run without any other Python code
until some other event happens and a decision has to be made, shown in figure
reactive simulation figure [16].
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Figure: Reactive simulation [16]
5.14 Controlled simulation
Now here we are talking about a controlled simulation, this simulation is a hybrid of
Python code and low-level code that combine to provide a full simulation and the
simulation objects are Python objects that might have representations in the lowerlevel code. In this type of simulation, the Python code does not include all of the
information required to actually run the simulation [16]. For example, there is a door
which is depending on the python object in a physical simulation. This object has
performed a task when operations such as opening and closing are performed. The
opening and closing of the door is contain the references to other game or
simulation objects and is able to interact with them directly [16]
In addition to the Python door object, there is a door object in the low-level code that
tracks more detailed information about the object, such as its exact open angle, its
current swinging velocity, and its 3D representation. The main point of these
simulations, object interact with each others, but the decision making and control are
the responsibility of the python object, because the python simulation will decides,
when the door is needed to start and stop the swinging the door. Showing figure in
the controlled simulation below, this approach is a higher functionality in this
language but they need small interface to the physical simulation. [16]
Figure controlled simulation through physical simulation [16]
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5.15 Parallel simulation
In a parallel simulation means two simulations run in parallel. One is used for lowlevel language runs very accurately at a level of granularity, with the help of low
level simulation is very accurate, run in a real time and be update accurately every
frame, such as rendering and animation. Now in second simulation runs in the
python at a course level of granularity, but it’s sufficient for making certain decisions
required for the simulations. This approach does require interaction between the
simulations to ensure that they stay in synchronization, and it also includes the
elements of reactive and controlled simulation. In this approach, the python code
has run the simulation at the level of requirements for game level decisions; main
thing all information doesn’t required rendering the world [16].
For example, in this approach, there are door objects in two simulations. Both
objects are capable of opening and closing, and the objects communicate with each
other to ensure that they keep their states synchronized. But in some cases, such as
on a server, the low-level door object might not exist, as the type of simulation it is
performing is not needed. In these cases, the higher-level door object is still able to
act function because it can act independently. Showing in the below figure of parallel
simulation [16].
Figure of parallel simulation [16]
This approach has the advantage of simulation; it can be run without the low-level
version of the simulation. This means that the Python could be run on a server, or
on a low-end client that doesn’t have graphical capabilities. It can also mean that
development on the Python version of the simulation can be performed
independently of the low-level simulation. This separation between the simulations
can allow progress to be made on game systems before the low-level simulation is
in place [16].
5.16 VARIABLE RATE UPDATING
In computer simulation, object updating is expensive. But the techniques is exist in
the game development to minimize the number of object update are performed. One
such technique is to vary the frequency at which objects are updated based on the
29
magnitude of their movement. Fast-moving or spinning objects must be updated
every frame, but slower-moving objects and stationary objects can be updated less
often without any loss in fidelity of the simulation. But In some conditions, this
method is helpful for take decreases amount of processing times required for
updating the simulation objects [16].
5.17 Light and shadows
Lightning is one of the most important things in Computer Graphics-art. Ever since
CG exists, artists wanted to create perfect copies of real life. One big problem was
lighting up the scene [26].
Where to put the different spots to get a half-decent result? Here we are solving the
problem of light and shadow. Firstly explain the 3 basic methods of lightning and
should help them to choose the right lightning technique for their game, industrial
and manufacturing departments [26].
5.17.1 Visual Perception: What We See Is Not Always What We Get
The majority of what we think we see at any moment is actually a virtual world
created by our brain. In reality, our eyes can detect details only within a 1.5° arc.
The rest of the eye’s detectors, which cover about 240°, are equipped only for
sensing minimal detail of colorless light. Our brain combines details from continuous
scanning with the peripheral image and our expectations to create what we believe
we see. When we view a flat-framed image, however, we tend to see exactly what is
there. [27].
The other motivation for controlled lighting is for use as a storytelling tool. Different
light quality, brightness, direction, and color can change the feel of a scene. This is
an important part of the visual story of a film. Let us take a closer look at these
elements of lighting [27].
5.17.2 Clock layout
The clock layout is very helpful for providing the location according to the lit object.
Subject is always present in the centre of the clock. The camera moving around the
subject but its location is either V or a H. Its movement is 3H, 6H, 9H and 12H to
account the three dimensions. Below figure give you the detail of the clock layout.
In 3H and 9H is produces the maximum texture out put are called edge lightening.
This is good for the better result of the objects detail. If we are stand in the back of
the object 12H, its mean light is in our back the output result is black object appears.
[27]. Let figure the clock layout and right one is the example of 12H.
30
Clock layout
12H position output
5.18 Light quality
Light is a single- point source in different situation, the creation of light is depend on
the source or power of light, so according to the my research there is mainly two
types of light creating ways, first is hard light, and it is different origin and direction.
This type of light has harder shadow with hard edges. The main reason of hard light
will give out the small textured on the surface, figure below left. Now the second
type is soft light, its fills the space and its directionless and it can be created with the
help of multiple reflections of various surfaces in the environment. This type of light
produces an equal amount of light hit on the every surface is called light casts. Due
to the lack of contrast, it creates the flat image [27]. Figure below center
Hard light
soft light
combinational light
Now this is not a type of original light, actually it is a combination of soft and hard
light. The main benefit of this light it will achieves a higher quality of effect, and its
will automatically increases the illumination in the dark shadow of a dark light
without adding additional shadows, Above figure right [27].
The previous light types describe opposite ends of a continuous spectrum. The
image that is in middle position is a light that throws out shadows and it has definite
direction with soft edge. The effect of the middle light is same like a as sunlight [27].
While deciding the use of light, there are two important types of aspects such as
texture and shadow. The small shadows are also a result of texture and texture is
dependent on the direction than the shadow [27].
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5.19 Light Direction
When we talking about the light, it is necessary to follow some direction, lighting is
relative to the direction the camera is facing. Lighting produce the flat look if
produces from the front panel. The reason when the light landing on the surface, no
shadow will produce because light is directly to the surface. But this is good for the
digital lighting to showing 3D object [27].
Light produces the flat look
In gamming and virtual world, or you can say that in digital world there is no physical
camera nor light is present. Usually, however, full frontal lighting is not desirable. As
the light moves away from the camera, and around the subject, the modeling or
three-dimensional texturing of the subject becomes more evident [27]. The edge, or
side, light reveals even small three-dimensional differences by casting shadows
from anything that is not facing the camera. In this way, the viewer can see details
that would otherwise be impossible to notice without examining the item in person.
To reveal these small details in digital rendering, we must perform either high levelof detail self-shadowing or an approximation such as bump mapping [27].
Casting shadow [28]
This is possible to improve the quality of texturing through light, if side light combine
with bump map then texture automatically improved. The only problem for machine,
its takes time for rendering, otherwise the ray-tracing will produce an accurate image
[27].
In virtual environment backlight is better approach as compare to the physical world;
the reason is that polygon light doesn’t allow for the refractive effect needed for
backlighting. This is reality that we do not need to render the back light in the virtual
world; the reason is that in virtual world camera has it self light [27]. Below figure
give you the result of the polygon when light put on the back side.
32
Light put on the polygon from the back side
5.20 Light techniques
There are typically three types of techniques of light in the scene. Three light
scenes, Sphere of light, mental rays
Roles of three lights [17]
This is the fact that light has no rules according to the standards’, but every scene
has its own lightening positions with the help of these three light scenes. The key
light is the man responsible for the main illusion of the scene and it’s create the
strong shadow with hard light, you can also observe in the left side of the picture
that give the example of the key light on her face. The normal amount of multiplier is
1 with a bright white color at the angle of 45 with some height. In virtual world
shadow doesn’t create automatically, you have to activate them. If we talking about
in real life, key light is come from sun and in room from lamp [29].
The fill light is also called the supplement of the key light, because its give the
smoothness of the scene and detail of the object. In real life every object omits and
emits parts of the light. The emitted light lights up other objects and gets omitted and
emitted again. This effect is called “radiosity” [29].
In virtual world these type of effect is more complicated while in simulation, that’s
why fill light is helpful for create the fake reflection, fill light not strong if we compare
with the key light, actually the multiplier ratio is 0.5 or lower and color depend on the
scene. This type of light has no specific place for direction, the only purpose to
clarify the object. And you can use the fill light through omni or spot light [29].
The back light define the object in a scene and it helpful to light up the boarder of an
image, it is place in the opposite side to the key light and its height little bit above.
Due to the same setting of a fill light, that why the shadow of this light is also same.
The only purpose of this light for opposing the fill light, so the realism will produce in
the scene [29].
Now we am talking about the sphere of light, actually this type of light give you the
originality of the object shadow, when it is put down on the uneven surface. Here
33
we am give you the tree example, as shown below, the left picture give you the good
output result, except the tree shadow is not present, here we need a shadow which
is generating a depth.
The two different output results left has no shadow and right generates the depth
Every thing in the virtual reality is not an easy task, actually creating real in 3D is
very complex, complex in a sense of settings, here we am talking about the E light is
use for the produce the real shadow according to the surface. E lightning bring you
the geosphere shadow of any object like tree [29].
Mental ray is another type of light which generate the physical correct simulation of
the light effects, including reflection, refraction and the whole scene illumination. As
we already mention that 3D virtual reality is very complex. So the mental ray is very
complex rendered, you can see below the picture left is rendered with the standard
scan line rendered using the 3 light technique. And the other one is rendered with
the mental rays with global illumination. Caustics effect is only possible and the
background is clearer as compare to the other one, these effects only possible with
the help of the mental rays. The only problem, mental ray take more time than the
other sanline rendered but you can generate the photorealistic picture with physical
correct lighting effects [29].
Scan line rendered light technique
mental rays light technique
34
5.21 Types of shadows
Light is the main part of the scene but without shadow nobody find the mood of any
scene in virtual reality. There are four types of shadows.
The primary shadow is created with the help of light but every object has a
shadow. Now the question arise what is the deference between shade and
shadow. Actually the lack of illumination is called shade but primary shadows
is obstructs the light and the illuminates the surfaces that receives the
shadow. The secondary shadows that can be generate with the cast on the
object and put background of the scene [27].
The tertiary shadows cast on the subject by the objects and background of a
scene, making them essentially the reverse of secondary shadows. The false
shadow is same as that of shadow , this shadow is generate in the sense of
frame, we mean some portion of a scene put in a frame, some in darkness
and some in light these limit are called the false shadow [27].
But in virtual reality user can generate multiple shadow, but it’s only feasible by the
certain amount of light setups. The primary shadow doesn’t take time in real time
games environments. Secondary shadow gives you the support in the place of
subject in the scene. Shadow have a its own density but shadow have light or heavy
density and illumination is totally depend on the shadow density, strong shadow
always generates the hard edges and little illumination whereas the soft shadow
have fades edges and little closer to the reality [27].
5.22 OpenGL and radiance
OpenGL (open graphics library) is a software interface to graphics hardware and it’s
used for writing the 2D and 3D interfaces. It have many functional and procedures
for generating the high quality graphics. They are used in virtual reality CAD and
different types of visualizations. It better performance than the Directx. It is only
rendered with the frame buffer technology because hardware is also follows the
same pattern [30].
The functionality consists of evaluators (used to model curves and surfaces),
selection (used to establish rendered primitives on the screen), feedback (which
returns GL results before asterization), display lists (used to designate a group of GL
commands for later execution by the GL), flushing and finishing (used to
synchronize the GL command stream), and hints [30].
The main purpose of the openGL is to hide the complexities of interface and
conflicting capabilities of hardware with the help of different programming
procedures. According to the experience of games, openGL is better generates the
output result, because openGL is work on the frame buffering but direct work on the
vertex shaders [30].
Radiance is basically computer software which is used for generating the realistic
image with the help of physical environment through proper calculation and
35
predicting the visible radiation in the space. It is free software for lighting the
rendered and its simulation [31].
By using accurate input into the program will give you the positive output, such as
manufacturing, industrial design and gaming technology. It also helps out specific
lightening fixtures and experimental lightning design and also enhanced the both
seculars and diffuses inter-reflection [31].
This software is mostly used in controlling and enhanced the environmental
lightning, actually there is three steps is involved during to create the whole
environment, first step to creating and converting a three dimensional description of
a physical environment or a scene, for example house interior, rooms, furniture, light
etc into simple geometric element that can be interpreted by the radiance packages.
In second step, setting up the lightning sources and its strength, and the last and
final step to rendered the original image with proper light and environmental effects
[31].
5.23 Future technological developments
There is lot of effort has been given in the field of virtual reality, it is still overvalued
terminology brings people to closer. Everybody talk, move, playing games, interact
with the peoples and touch thing with the help of virtual technology. As the time
passes, many real applications coming into people life, many applications is develop
for many purposes e.g. architecture, visualization, entertainment, manufacturing,
augmented reality, art, education and training, medical, virtual communities and
distributed VR. Further ill describe the terms and its benefit in VR [32].
As you know that, in virtual tool every body can create 3D object and demonstrate
them. So it is very useful for user to explore a 3D scene in real time, user can see
the architectural design or easily manipulate them. Communication is the most
important part of the any successful application with the user before design any
product. In virtual reality illustration is the main part for demonstration any scene or
environment in front of the user, because of computer 3D graphics performance.
And this increasing better output, user will see the more visual detail of polygons
and environmental effects. With the interaction of VR systems user can move
around any restriction and beyond the limits of physics [32].
Visualization is also a very important part of present days; user can resemble the
architectural walk through on many aspects. With the help of VR system,
visualization gives you the power for visualizing complex equipment and fixed it [32].
The major resources are used for the gamming and entertainment world. And this is
also a most profit able area in the field of virtual reality. Many companies are
producing game and its hardware related and according to the principles of VR, e.g.
VR gloves and HMD. Virtual reality is also helpful for creating the manufacturing
objects, and user can interact in 3D environment with VR hardware’s, nowadays the
uses of VR system is testing, various controlled and its components, simulating
airflow and aerodynamic performance of car [32].
In art, virtual reality is present, in future user will interacts virtual pointing devices in
a cave systems, this is not sure these application give the better output or not. And it
is also use in the fields of training and education e.g. in flight simulator this is one of
36
the oldest application in the field of VR. Pilots are trained in virtual environments and
fly airplane virtually [32].
People can interact through networks communication, since the start of p2P
networks. On behave of virtual reality system evolvement is fully integrated and
work cooperatively through a virtual world, patient will be operated from the
distance, NASA communicates and interact with the people in space and explore
different investigation. But all these application need more reality because it can be
work with some limits, actually the reality is limit less. We are sure near future virtual
reality will bring something new and its worth is more [32].
37
6
EMPIRICAL STUDY
__________________________________________________________________________
Here we am comparing the two environments one is CRT display and the other is
CAVE in the standpoint of games, manufacturing and industrial design, but the main
concept is still present are called virtual reality.
Virtual reality systems are used for a variety of application like games, industrial
design and manufacturing department. The purpose of research is the interaction of
virtual reality appearance and performance in cave and normal desktop display with
the help of flight simulator. In this environment, we only consider the visibility of an
virtual environment like interface, light and shadows effects and simulation of an
object either polygons and physical appearance [33].
According to my observation, the user involvement in the game is depending on the
reality and the effectiveness of the game. The cave environment is so called
immersive as compare to the desktop display [33].
If we compare the desktop and cave environment, one or two users may sit
comfortably and view the virtual environment at same time in a normal PC with 17
inch screen size. But involvement is only possible for one person. But in cave many
user can interact in the same virtual environment, if an environment is created with
three or four sided projection. [33].
Before an experiment, it is seem very difficult to say that which one is more closely
to the user, where user feel environment problem in which scenarios. The
development of the flight simulator is very challenging work, the only reason of
complexity of the simulation and environmental effects.
6.1
Generic model
A flight simulator normally work on the seven sub systems, simulation models,
cockpit instruments, visual cueing system, motion cueing system, audio cueing
system, instructor station and cockpit controls & force feedback system. The
relationship of these components is shown in fig.1. [34].
Fig 1: flight simulation functional model [34].
38
These facilities in the flight simulator are very helpful for the users, visual cue, audio
cue, and force feedback signal and motion indication. The instructor is in charge of
the educational aspects of flight simulation. It is the person who decides what
mission will be run, and under what conditions. [34].
6.2
Software and hardware
There are many software and hardware used for flight operation, simulation and its
environmental effects. We chose MATLAB/ Simulink to build simulation models,
VAPS for drawing cockpit instruments, MultiGen Creator for modeling virtual visual
environment which was driven by MultiGen Vega. Not only visual, the audio files
were called by Vega too. The whole system consists of 11 PCs as a cluster shown
in picture 1, hydraulic driven force-feedback system, digital geometry and soft edge
correction machine (Equipe 3ch-ProMap), 3 projectors (Equipe Contour 300), 2
speakers, a virtual prototype of motion system and ANOVA for analysis the
participants results [34].
Cock pit picture
11 computer cluster
Now here ill give you the explanation, why is it necessary and tell you how the
overall virtual environment will give you the better output. When we talk about
desktop computer with 17” screen monitor, the user can not feel him or her present
in the virtual environment. Instead of cave, a virtual environment made up of multiple
screens. And user can interact in the interface and environment with the help of
head tracking device. More over user can move within the physical cave from 0* to
180* or in some cases 360*.
When a user can interact in the virtual environment, we must manage the tradeoff of
physical and virtual navigation in the below table.
39
Spatial understanding
Directness
Navigation interface
Physical navigation
Higher
More direct
No explicit UI, body
provide input
Virtual navigation
Lower
Less direct
Requires a dedicated
navigation UI (button, etc)
Generality
Fatigue
Input devices
Not always sufficient
Higher
Must be mobile
Can always be used
Lower
Any device can be used
Tradeoff of physical and virtual navigation [35]
6.3
Experiment design
The purpose of this experiment was to conclude where the user can feel
comfortable in the virtual environment along with all properties; either desktop
screen size or the large screen cave. Cave environment should be the faster and
accurate as compared to the desktop environment.
We take some participants 4 male and 4 female, 6 participants are the graduate
student and 2 of them is master. Each person has to assign a task for two types of
display. These participants will check the environmental effects, simulation and the
interaction with the cockpit. This experiment took 4 days for full and final evaluation.
6.4
System overview
Before starting experiment, ill give you some properties in CRT and cave
environment. In CRT have 17” screen with 3D CAD and in cave three sided screens
with 4” x 120” x 120”. The cave is compiling with four computers with dual Intel CPU
2.0GHz and 1 GB RAM, instead of this normal desktop computer has 512 RAM with
1.7 GHz CPU. The software is totally controlled all types of rendering and input
devices.
Participants start experiment form the desktop and each task, take 25 min for
checking and 10 min for filling the form before and after the task. And the total time
for all tasks will take 70 min.
6.5
User interface
In CRT, the entire cockpit environment is display in one computer, and if the users
need to watch the left or right side of the environment, they need to be change the
view. And all type of instrumental detail of the cockpit is display in the monitor,
showing in the lower portion and the above portion is used for outer environment.
40
But in CAVE, the middle screen is used for the cockpit panel and the window of the
cockpit, left and right side screen showing the left and right side of the cockpit and
environment view.
6.6
Training
Before start experiment, participants were given three to five min to become familiar
with the display configuration and navigation systems in the CRT case and in the
CAVE environment. The participants give a try to check the working and dynamically
changing viewpoint through head position
6.7
Experiments
Before starting experiments, we clearly point out the experiment in the CRT
environment which all the empirical result is taken by my self but in case of cave the
data is acquire from the previous research papers and experiments.
6.7.1
CRT- Experiment
Before starting experiment, each participant check the eyes vision ability, mean
corrected-to-normal vision, and all participants prescreened to have binocular depth
acuity of at least 200 arc second. Each participant have to fill the form, previous
knowledge and experience and a short question e.g. age, sex, gender etc. In this
study the whole environment is totally immersive by the help of SGI Onyx 3200
infinite reality [37], because this will give you the 141 million polygons per/s and
unbelievable 3.8 billion pixel per/s of sustained performance [36].
During the desktop condition, monitor is used and situated in the centre of the
immersive room. The user will sitting in the middle of the immersive room, because
observing the similar visual angle all viewing condition. The resolution for all the
displays equipment is 1024* 768 pixels and all the time the stable refresh rate of
96Hz all the time. And the frame rate will be same in 10 frame/ sec and illumination
will be very near to darkness [37].
Participant used joystick to move forward and backward and to rotate clockwise and
anti clockwise. The model aircraft Boeing 747 for is used for interact the
environment and its simulation. This data set is written in the C++ using OpenGL
performer and CAVElib. These all software is used for the displacement of the
aircraft and helpful for the recording the user performance. To find the accuracy, all
rendering distances and the virtual distances from the user, Boeing data set is fixed
at the level of 90% [37].
41
Figure: runway, high altitude view and user interact with flight simulator
6.7.2
Cave- Experiment
In CAVE, the room is fully immersive display with four sided display, but in the case
of flight simulator the only front, left and right side of the screen working. Electro
home 9500 CRT projectors are used for project images on the screens. Even in
cave user can move in the wall configuration but for the accurate output. That’s why;
user can sit in the immersive environment, same as desktop computer.
Figure: Cave environment in the cockpit
The resolution for all the displays equipment is 1024* 768 pixels and all the time the
stable refresh rate of 96Hz all the time. And the frame rate will be same in 10 frame/
sec and illumination will be very near to darkness. For the input user used 360
degree-of-freedom intersense IS9000 ultra sonic tracker and mouse for takeoff,
landing and movement of left and right direction [37].
42
7
RESULTS
__________________________________________________________________________
So now the time is for output of the result, these two experiments give me a three
output results, first part of the result give me the performance of the flight simulator,
which is directly related to the simulation of the plane, and it’s all the environmental
effect. The second result type gets from the questionnaire. And in the last one is my
observation during the running task [38].
7.1
Task Presentation
Below chart shows the average user performance in Cave and CRT environment.
Out off eight users was place the more quality appearance in the cave as compared
to the CRT display. Only one user was not completes the experiment in time,
because they got shaky in the cave, that’s why we couldn’t include in the chart [38].
Average Performance
200
Quality
150
CAVE
100
CRT
50
0
CAVE
CRT
1
2
3
4
5
6
7
148
123
117
88
180
82
78
98
87
91
50
90
88
85
User
Average performance of the user in flight simulator [38]
7.2
Questionnaire
This is my second result output on the bases of the questionnaire; here ill give you
the brief explanation with the help of user form before and after the experiment. This
is very clear all the student were student of computer science department, I also
asked the entire student, who many student have 3D program experience, five
student have no experience and the other have little bit. But not of all have a virtual
reality experience especially in the cave environment [38].
In the pre-questionnaire, users just fill the information about self and interests,
instead of post-questionnaire, here we asked the student to categories the ten
43
questions according to the both environment experience, given above the question
detail and calculation in the range in between the 1.0 to 10.0 [38].
No.
1
2
3
4
5
6
7
8
9
10
Questions
How was the effectiveness of the user interface
System help out to perform the task
Which system is easy to use (once you had learned)
In which system the simulation is near to real
How the quality of front panel appears (light and object shadows)
Which environment you experience efficiency to perform the task
Where you feel comfortable
In which environment your confidence was boost up
In which environment you feel real enjoy
Your preference of future use
Cave
6.1
5.5
6.9
5.7
5.5
7.8
7.0
6.9
7.5
6.5
Cave average result from the post-questionnaire
No.
1
2
3
4
5
6
7
8
9
10
Questions
How was the effectiveness of the user interface
System help out to perform the task
Which system is easy to use (once you had learned)
In which system the simulation is near to real
How the quality of front panel appears (light and object shadows)
Which environment you experience efficiency to perform the task
Where you feel comfortable
In which environment your confidence was boost up
In which environment you feel real enjoy
Your preference of future use
CRT
3.9
4.1
4.0
4.5
4.7
4.4
3.5
4.0
3.5
3.2
CRT average result from the post-questionnaire
After the above result, cave take a higher scored as compared to the CRT. But in
some case the user ranked CRT, especially in the 4, 5 questions. But overall Cave
provides a best simulation and environmental effects.
7.3
Participants Proposal
During experiment many participants give suggestion, likeness and dislike about the
both environment for improvement. Two students liked cave environment, because it
give you the full immersive environment and user can interact with the virtual
objects. Mostly student was not satisfied with the CRT environment. Some students
give a suggestion to counterbalance the screen, or to add at least two more screens
for creating the virtual environment (flight simulator). And the interaction in the CRT
monitor is not leading. At the end of this discussion, mostly student was very
impress the visualization of cave environment [38].
44
7.4
Observation
We am very astonished, that mostly user was easily learned and interact the both
environment specially the Cave. During experiments we evaluate that, the clearness
of the display was not good in the cave as compared to the CRT. The reason is the
brightness and contrast in dull through the projectors, that’s why mostly users
request the higher the resolution in cave [38].
In CRT the display and rendering quality is good but the problem is only with the
frame rate. As we already mention above, frame rate is same in both the
environment, but during the experiment user feel problem in the CRT. It is very
impressive; user can feel very comfortable while controlling the aircraft in the cave
environment. This result give me that cave interface is more natural as compared to
the CRT, but few drawback of both environment. we could not expect that user was
feel difficulty selecting the functionalities while in the cockpit panel, according to my
observation cockpit panel is not look at complete at same time [38].
At the end we finally say that, cave got the maximum score as compared to the
CRT. But we also say that, we were found the difference is just because of the
interacting equipments. This statement is doesn’t mean, CRT give you a natural
interface.
45
8
OVERALL DISCUSSION
__________________________________________________________________________
This master thesis revolves around the phenomenon of virtual reality. During this
virtual reality oriented documentation, the introduction emphasizes on the basic
information regarding the context of virtual reality and the purpose that why this field
interested me for research. This research mainly focuses on the specific questions
related to the virtual environment. The answers to the question mentioned in this
research provide the solution and the techniques for simulation, lights and shadow
which is helpful for the development of better environment, enhancement and
interaction with the user.
Our lives are becoming dependent upon the advancements of Information
technology; because of this the purpose of the thesis is to create a relationship
between the human and the virtual environment and how they interact with these
types of virtual environment.
As an analysis from the theoretical and empirical study (comparison of software
within the two different environments has been carried out i.e. one is CRT and the
other is CAVE), It was recognized that reality is the most important part of
interaction of the user. It was not the case before the experiment but the comparison
give me an idea about, how simulation and other environmental effect play an
important role for the user interaction.
When we talking about result, I have done one experiment out of two, these two
experiments give me a three output results, first part of the result give me the
performance of the flight simulator, which is directly related to the simulation of the
plane, and it’s all the environmental effect.
The second result type gets from the questionnaire; these are ten questionnaires for
two different environments and the purpose is to find the answer of the proposed
questions. Especially these questions related with the simulation, interface and its
light and shadow effectiveness. One thing is very important in these two experiment
reader particularly find the light and shadow in the form of results and these result
give me the numerical values. And in the last one is my observation during the
running task.
Finally it is experienced that virtual reality is very supportive for the development of
the industrial design and manufacturing departments. This is only applicable if the
interfaces and interaction of the user has been under operation depending upon the
specific virtual environment. Many virtual environments failed just because of the
less quality of the interface and its environments.
Conclusion
After analysis of theoretical and empirical study, we conclude that
•
Environment effects and simulation is more important.
•
Reality is more dependent on the environment.
46
•
The clearness of the display was not good in the cave.
•
The frame rate problem in CRT
•
This is very impressive; user easily controlled the aircraft in the cave. virtual
reality is very supportive for the development of the real games, industrial
design and manufacturing departments
47
SUMMARY
__________________________________________________________________________
After empirical study and answering the questions of this thesis, we fully believe that
it is very important for virtual reality is to first create an environment of a game,
industrial design and manufacturing for realistic out put for the user point of view.
The most essential is how the system works near to realism. How the critical
success factor of virtual reality influences these benefits
We believe that it is very necessary to have good approach to compare or to find the
effective and enormous environments that does can be used and helpful for
producing the real environments. According to the game scenarios, one should start
from the interfaces and environmental effect. And compare them into to different
situations, and then you can find the effectiveness of the environment.
So that’s why we are compared the two virtual environments, which one is more
near to the user in the sense of reality. After some analysis of these environments
and their out come form the questionnaires and observation,
After empirical study we discovered that, not every thing is easy to measure, only
human contribution will demonstrate the actual quality of the product and the
involvement of the user.
We hope this thesis will helpful for improving the quality of an environment, either in
the case of manufacturing or in any field of designing
My research will give you all the intangible benefit for the future work in the sense of
new technology either in game or in manufacturing.
Future work
• TD vision has been trying to develop the 3D view near to the reality
• Future can be done to implement this approach in the field of augmented
reality.
48
REFERENCES
__________________________________________________________________________
This chapter gives references about the research material which we have studied
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Sharples, Sue Cobb, Amanda Moody, John R. Wilson, Virtual Reality
Applications Research Team (VIRART), School of Mechanical, Materials and
Manufacturing Engineering, University of Nottingham, University Park,
Nottingham NG7 2RD, United Kingdom, 1 October 2007
[34]. PC Based High Quality and Low Cost Flight Simulator, Zhang Lei, Jiang
Hongzhou, and Li Hongren, School of Mechatronics Engineering, Harbin
Institute of Technology Harbin, Heilongjiang Province, Chin, August 18 - 21,
2007, Jinan, China
[35]. Move to Improve: Promoting Physical Navigation to Increase User
Performance with Large Displays, Robert Ball, Chris North, and Doug A.
Bowman, April 28-May 3, 2007
[36]. SGI® Onyx® 3000 Series with Infinite Performance™ Graphics, The
Ultimate
in
Interactive
Graphics
Performance,
http://www.sgi.com/pdfs/3211.pdf
[37]. Comparing CAVE, Wall, and Desktop Displays for Navigation and Way
finding in Complex 3D Models, Colin Swindells1, Barry A. Po1, Ima
Hajshirmohammadi2, Brian Corrie3 John C. Dill2, Brian D. Fisher1, and
Kellogg S. Booth1
[38]. A Comparison of a Cave and a Fish Tank VR System for Counting Biological
Features in a Volume, Jurgen P. Schulze and Andrew S. Forsberg
http://vis.cs.brown.edu/docs/pdf/Schulze-2004-CCF.pdf
51
APPENDIX
__________________________________________________________________________
Virtual Worlds Comparison Chart
The following is a comparison table of virtual worlds, as of August 2007. In this table
you can find the detail overview of virtual world under difference headings and its
comparison related to the other virtual world.
Virtual
World
Active
Worlds
OS
Own
Build or Script
Comm
Cost per Target user & Edit
land or Education
design conten
.
sell
month style
avatars
ready
content t
Events
items
PC & Free /
Linux $6.95
Young girls
Free
Fashion,
social
Free / Kids, Games
$5.95 and Activities
Training, ELearning,
Contract
Serious
Games
Social; Topdown
Free
overview,
sprites
Barbie
Girls
PC
Club
Penguin
PC &
Mac
Forterra
Systems
PC
Gaia
Online
PC &
Mac
Habbo
Hotel
PC &
Free
Mac
PC &
Free
Mac
Kaneva
Neopets
Teen
Second
Life
Second
Life
PC & Free /
Mac $7.95
PC & Free /
Mac $9.95
PC & Free /
Mac $9.95
The Sims
PC
Online
There
Webkins
PC
General;
Exploration
No
Can code
selling
No
No
Neither No
No
Neither No
Can
code
No
Sorta
Teens; Social
No
Neither No
Teens; Social
No
Sorta
Kids and
teens; Minigames, social
Teens only;
3D, Creation,
social
18+ only; 3D,
Creation
No
Can code
No
No
No
No
No
Can code
Can code
$9.95/m General;
Social; 3D
o.
No
Free /
$9.95
Free
Limite
No
d
No
Neither No
PC
PC &
Whyville
Free
Mac
General;
Social
Social
Kids and
teens; 2D
Can
code
No
No
No
No
selling
Neither
52
sprites;
Educational
Zwinktopi
PC &
a
Free
Mac
Teens; Social
No
No
Neither No
http://www.virtualenvironments.info/
53